No evidence that omission and confirmation biases affect the perception and recall of vaccine-related information

Abstract

Despite the spectacular success of vaccines in preventing infectious diseases, fears about their safety and other anti-vaccination claims are widespread. To better understand how such fears and claims persist and spread, we must understand how they are perceived and recalled. One influence on the perception and recall of vaccination-related information might be universal cognitive biases acting against vaccination. An omission bias describes the tendency to perceive as worse, and recall better, bad outcomes resulting from commissions (e.g. vaccine side effects) compared to the same bad outcomes resulting from omissions (e.g. symptoms of vaccine preventable diseases). Another factor influencing the perception and recall of vaccination-related information might be people's attitudes towards vaccines. A confirmation bias would mean that pre-existing pro-vaccination attitudes positively predict perceptions of severity and recall of symptoms of vaccine preventable diseases and negatively predict perceptions of severity and recall of vaccine side effects. To test for these hypothesized biases, 202 female participants aged 18-60 (M = 38.15, SD = 10.37) completed an online experiment with a between-subjects experimental design. Participants imagined that they had a 1-year old child who suffered from either vaccine side effects (Commission Condition) or symptoms of a vaccine-preventable disease (Omission Condition). They then rated a list of symptoms/side effects for their perceived severity on a 7-point Likert scale. Finally, they completed a surprise recall test in which they recalled the symptoms/side effects previously rated. An additional scale was used to measure their attitudes towards vaccines. Contrary to the hypotheses, perceptions of severity and the recall of symptoms/side effects were not associated with experimental condition, failing to support the omission bias, nor did they interact with attitudes towards vaccines, failing to support the confirmation bias. This cast doubt on the possibility that the spread of anti-vaccination claims can be explained by these particular universal cognitive biases.

Prestige Does Not Affect the Cultural Transmission of Novel Controversial Arguments in an Online Transmission Chain Experiment

“…Supporting this, the full sample of participants was initially slightly against the replacement of textbooks by computer tablets at schools (Median = −1). However, participants' attitudes towards tablets did not predict recall, which contradicts the confirmation bias explanation (see also Jiménez, Mesoudi, & Tehrani, 2020).…”

Fact vs Fallacy: The Anti-Vaccine Discussion Reloaded

“…There are biases of omission (believing something despite a lack or paucity of evidence); confirmation bias (favoring arguments that support one’s pre-established position); false or imagined correlations between events; the “availability heuristic” which gives undue weight to certain events at the expense of others; and cognitive dissonance, in which perceived “conflicting evidence” may lead one to resolve the internal conflict by selecting an incorrect but seemingly less dangerous solution. Parental vaccine hesitancy has been correlated with information avoidance and omission bias [ 28 , 29 ]. There is also a naturalist bias in the anti-vax community, which maintains that vaccines are manmade and therefore unnatural, so that they confer an immunity that is different and inferior to natural immunity [ 30 ].…”

“…While the role of confirmation bias in vaccine hesitancy and anti-vax sentiment remains disputed [ 29 , 33 ], social media tends to artificially generate confirmation bias by its unilateral presentation of certain viewpoints [ 40 ]. Such bias may extend beyond user-generated social media to mainstream and other news media outlets [ 41 ].…”

Framing messages for vaccination supporters.

“…However, if arguments are to be further spread by provaccine individuals, these individuals should not only accept the arguments, but they should also be able to memorize them and be willing to transmit them to others. Although the field of cultural evolution has long paid attention to memory and willingness to transmit in theoretical (Boyer, 2018; Morin, 2015) and empirical work (for a recent review, see Miton & Charbonneau, 2018; for applications to vaccination, see Jiménez, Mesoudi, & Tehrani, 2020; Jiménez, Stubbersfield, & Tehrani, 2018; Miton & Mercier, 2015), only one of these factors (memorization) has been examined in the case of vaccination (Pluviano, Watt, & Della Sala, 2017).…”